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Biomedical subjects

T Sakaki

Publications and source records attributed to T Sakaki.

At least 217 records · Page 12Linked to original sources
PubMed1994

Response of pial vessel diameter and regional cerebral blood flow to CO2 during midazolam administration in cats.

Midazolam has been demonstrated to preserve the response of cerebral blood flow to CO2. However, the responsiveness of cerebral vessels or microcirculation during midazolam administration related to alteration of cerebral blood flow has not been explored. The purpose of this study was to examine the effects of midazolam on cerebral microcirculation. Nine cats were paralyzed and mechanically ventilated under nitrous oxide/oxygen anaesthesia. Using the closed cranial window technique and laser Doppler flowmetry, diameter of pial vessels and regional cerebral blood flow (rCBF) were examined on the surface of the cerebral cortex which was perfused by the middle cerebral artery. Before midazolam administration, haemodynamic variables, blood gases, rCBF, and diameter of pial vessels were determined as a control under normocapnia, hypocapnia, and hypercapnia conditions. After midazolam administration, given initially at 0.8 mg.kg-1.min-1 for 10 min and subsequently at 0.04 mg.kg-1.min-1 (total dose 10 mg.kg-1), the same variables were again analyzed. With regard to CO2 responsiveness, an 8.85% increase in rCBF was demonstrated for a Paco2 elevation of 1 kPa before midazolam administration, compared with a 7.47% increase after midazolam administration. With regard to the correlation between CO2 response and vessel diameter, arterioles less than 50 microns in diameter were more sensitive than those more than 50 microns in diameter, although there were no significant differences before or after midazolam administration. We conclude that CO2 responsiveness is preserved in terms of rCBF and vessel diameter after high doses of midazolam (10 mg.kg-1) in cats.

Animals↗
PubMed1994

Correlation of E- and P-cadherin expression with differentiation grade and mode of invasion in gingival carcinoma.

The expression pattern of two Ca(2+)-dependent cell-cell adhesion molecules, E- and P-cadherin (CD), in 25 primary gingival squamous cell carcinomas (SCC) was examined immunohistochemically. The occurrence of reduced-type expression of both E- and P-CD increased significantly with the grade of carcinoma differentiation, culminating in a complete loss of P-CD in poorly differentiated SCC. The occurrence of reduced-type P-CD expression also increased significantly with the mode of invasion, as was the case with E-CD. Furthermore, no P-CD molecules were detected in one of the six SCC having a diffuse, cord-like invasion and in three of the six having a diffuse type of invasion. These findings suggest that the down-regulation of these cell adhesion molecules closely correlates with the differentiation grade and mode of invasion of gingival SCC.

Cadherins↗
PubMed1994

Specific changes in human brain following reperfusion after cardiac arrest.

BACKGROUND AND PURPOSE: Very few reports are available on serial changes in human brain after cardiac arrest. The primary objective of this study is to investigate sequential neuroradiological changes in patients remaining in a persistent vegetative state following resuscitation after cardiac arrest. METHODS: We repeatedly studied eight vegetative patients resuscitated from unexpected out-of-hospital cardiac arrest using computed tomographic (CT) scanning and high-field magnetic resonance (MR) imaging at 1.5 T. RESULTS: In seven of the eight patients, CT scans obtained between days 2 and 6 features symmetrical low-density lesions in the bilateral caudate, lenticular, and/or thalamic nuclei. These ischemic lesions were persistently of low density on serial CT scans. In these seven patients, MR images demonstrated what were thought to be hemoglobin degradation products derived from minor hemorrhages localized in the bilateral basal ganglia, thalami, and/or substantia nigra. Diffuse brain edema in the acute stage and diffuse brain atrophy in the chronic stage were consistent neuroradiological findings. No abnormal enhanced lesions were demonstrated by CT scans. CONCLUSIONS: The most characteristic findings on high-field MR images were symmetrical lesions in the bilateral basal ganglia, thalami, and/or substantia nigra with specific changes suggestive of minor hemorrhages that were not evident on CT scans. We speculate that these minor hemorrhages result from diapedesis of red blood cells in these regions during the reperfusion period through the endothelium disrupted by ischemia-reperfusion insult.

Adult↗
PubMed1994

Preparation of 6(1),6n-di-O-(tert-butyldimethylsilyl)-cyclomalto-octaoses.

Four positional isomers of 6(1),6n-di-O-(tert-butyldimethylsilyl)- cyclomalto-octaose (n = 2-5) were prepared by reaction of cyclomalto-octaose (1, cG8) with tert-butyldimethylsilyl chloride in pyridine, and were isolated by high-performance liquid chromatography. The regiochemical determination of those positional isomers was performed by comparison with authentic compounds, prepared from 6(1),6n-di-O-trityl-cG8s (n = 2-5).

Carbohydrate Sequence↗
PubMed1994

Medulloblastoma associated with cysts and calcifications--case report.

An 11-year-old boy presented with medulloblastoma occurring in the cerebellar vermis. Computed tomography and magnetic resonance imaging revealed numerous cysts and calcifications in the tumor. The tumor was subtotally removed and cellular synchronization radiation therapy given. He was discharged without neurological deficits. Histological examination showed the cysts represented necrotic foci. Macrophages, which appeared around the necrotic foci, were important in the development of the calcifications via proliferation of collagen fibers.

Brain↗
PubMed1994

Experimental study of the mechanism of seizure induction: changes in the concentrations of excitatory amino acids in the epileptic focus of the cat amygdaloid kindling model.

L-glutamate (Glu) and L-aspartate (Asp) are two major excitatory amino acids that may be involved in seizure susceptibility and seizure induction. The concentrations of Glu and Asp were measured by microdialysis in the epileptic focus in a cat amygdaloid kindling model. Sequential changes in Glu and Asp (before, during, and after seizure) were measured in the partial seizure (S4) and generalized seizure (S6) groups. By stimulation at and 50 microA below the partial seizure-triggering threshold in the S4 group and the generalized seizure-triggering threshold in the S6 group, Glu was released from the epileptic focus in the S4 group, and both Glu and Asp were released in the S6 group after seizure and stimulation (below threshold), and the amount of Glu and/or Asp release determined seizure induction. Excitatory amino acids may be the trigger of seizure induction in the cat amygdaloid kindling model.

Amygdala↗
PubMed1994

Pleomorphic adenoma of the lacrimal gland manifesting as exophthalmos in adolescence--case report.

A 16-year-old girl presented with a pleomorphic adenoma of the lacrimal gland manifesting as left painless exophthalmos which had persisted for 3 years. Computed tomography revealed a tumor about 15 mm in diameter in the superolateral site of the left orbit. The tumor was removed completely by combined orbitofrontal craniotomy through a transcranial approach. Histological examination demonstrated the growth of tumor cells as glandular cavities or sheets, with myxoid and partly chondroid connective tissue stroma. Pleomorphic adenoma of the lacrimal gland is unusual in adolescents.

Adenoma, Pleomorphic↗
PubMed1994

Strategies to improve the outcome of carotid endarterectomy.

The outcomes of carotid endarterectomy (CEA) including long-term results in 121 patients (126 procedures) were retrospectively analyzed to identify the causes of operative morbidity. The angiographic internal carotid artery (ICA) stenosis was severe (> 70%) in 62 patients and moderate (50-70%) with ulceration in 64. The arterial wall was sutured primarily in 91 patients and with patch graft in 35. The outcomes 3 months after operation were good recovery in 86 patients, moderately disabled in 20, severely disabled in 11, and death in four. Three patients suffered operative morbidity (2.5%). During follow-up, three patients (2.6%) suffered transient ischemic attack on the operative side due to middle cerebral artery stenosis (50%) or ICA occlusion at the origin, and recurrent stenosis (40%) of the common carotid artery and ICA (1 each). In the latter two cases, the artery was primarily sutured. Improved therapeutic results require use of patch vein graft for the arterial wall suture, checking of the CEA patency, and prevention of intracranial ischemic events and hemorrhage due to associated lesions.

Adult↗
PubMed1994

Recurrence of ICA-PCoA aneurysms after neck clipping.

Between 1975 and 1992, 2211 patients underwent aneurysmal neck clipping at the Nara Medical University clinic and associated hospitals. The aneurysm in 931 of these patients was situated at the junction of the internal carotid artery (ICA) and posterior communicating artery (PCoA). Seven patients were readmitted 4 to 17 years after the first surgery because of regrowth and rupture of an ICA-PCoA aneurysmal sac that had arisen from the residual neck. On angiograms obtained following aneurysmal neck clipping, a large primitive type of PCoA was demonstrated in six patients and a small PCoA in one. A small residual aneurysm was confirmed in only two patients and angiographically complete neck clipping in five. Recurrent ICA-PCoA aneurysms were separated into two types based on the position of the old clip in relation to the new growth. Type 1 aneurysms regrow from the entire neck and balloon eccentrically. In this type, it is possible to apply the clip at the neck as in conventional clipping for a ruptured aneurysm. Type 2 includes aneurysms in which the proximal portion of a previous clip is situated at the corner of the ICA and aneurysmal neck and the distal portion on the enlarged dome of the aneurysm, because the sac is regrowing from a portion of the residual neck. In this type of aneurysm, a Sugita fenestrated clip can occlude the residual neck, overriding the old clip. Classifying these aneurysms into two groups is very useful from a surgical point of view because it is possible to apply a new clip without removing the old clip, which was found to be adherent to surrounding tissue.

Adult↗
PubMed1994

[Thoracic outlet syndrome due to first rib anomaly: a case report].

Compared to cervical rib, first rib anomaly is less familiar to us as a cause of thoracic outlet syndrome. We report a case of thoracic outlet syndrome due to first rib anomaly. A 50-year-old man was admitted to our hospital because of right arm pain when his arm was raised up. Chest X-ray showed an abnormal right first rib which made a J-shaped curve and was attached to the second rib. A palpable mass was noted in the supraclavicular region. Angiography revealed complete occlusion of the right subclavian artery in the Allen test position. During conservative therapy for two months, the symptom was gradually getting worse. We performed resection of the right first rib and anterior scalenotomy by the supraclavicular approach. The patient made a good recovery after the surgery. Postoperative angiogram showed no stenotic lesion of the right subclavian artery. If a patient has complaints suggesting compression of the subclavian neurovascular bundle, we should be careful not to overlook the first rib anomaly on chest X-ray.

Humans↗
PubMed1994

[Ultrastructural morphological changes of cortical microvessels following transient cerebral ischemia--a transmission electron microscopic study].

Post-ischemic hypoperfusion may play a significant role in reperfusion injury. Since there is no established treatment for hypoperfusion, however we decided to explore the morphological cause of post-ischemic hypoperfusion. In this study we used transmission electron microscopy to investigate the capillaries in ischemic/reperfused neocortex induced by 2 hours of middle cerebral artery occlusion followed by either 3 or 24 hours of reperfusion in 14 cats. Post-ischemic hypoperfusion was confirmed by measuring regional blood flow through a cranial window just above the left ectosylvian gyrus, which has poor anastomosis. A greater number of endothelial microvilli and capillary endothelial cell swelling were detected in the ischemic/reperfused neocortex, when compared with contralateral control neocortex. Especially after 24-hour reperfusion, collapse of some capillaries was observed with severe perivascular glial swelling and adhesion of PMN leukocytes to the endothelium. These findings yielded the following statistically significant results. 1) The number of endothelial microvilli in the ischemic/reperfused neocortex (mean +/- SD/1 blood vessel = 6.58 +/- 4.32) was significantly greater than in the control neocortex (3.13 +/- 2.68, p = 0.0001). 2) The ratio of capillary inner diameter (ID) to outer diameter (OD) in the ischemic/reperfused neocortex (ID/OD%, mean +/- SD = 75.4 +/- 16.7) was significantly smaller than in the control neocortex (89.2 +/- 10.8, p = 0.0001), indicating endothelial cell swelling. We concluded that these ultrastructural changes might be the cause of the multifactorial development of post-ischemic hypoperfusion, and that especially the number of endothelial microvilli and the endothelial cell swelling ratio might serve as morphological indicators of therapeutic efficacy for reperfusion injury in experimental studies.

Animals↗
PubMed1994

[Malignant parasagittal meningioma appearing as a large subcutaneous mass].

We present a rare case of malignant meningioma appearing as an extracranial soft-tissue mass. A 34-year-old male was admitted with left parietal subcutaneous soft-tissue mass. Neurological examination on admission revealed right leg monoparesis and papilledema. Skull X rays showed hyperostosis of the left parietal bone. There was no evidence of bony destruction. CT and MRI showed a tumor with a large intracranial component, which was homogeneously enhanced. The tumor was totally removed by left ostoplastic craniotomy. The light-microscopic examination showed a meningothelial meningioma accompanied by malignant components with necrotic foci and mitotic figures. Tumor cells had invaded all the layers of the skull via the Haversian canals. We propose that hyperostosis with tumor invasion through all three layers of the skull should be considered as a malignant feature.

Adult↗
PubMed1994

[Cisplatin-etoposide chemotherapy of an embryonal carcinoma arising in the basal ganglia of the cerebrum: a case report].

Cases of embryonal carcinoma arising in the basal ganglia are rarely reported. According to the literature available, only 5 cases of embryonal carcinoma, arising from the basal ganglia, have been reported to date. This paper reports one such case we recently encountered. The patient was a 15-year-old boy. He was first admitted to another hospital because of occasional headache and vomiting. During the hospital stay, CT scans revealed abnormalities. For this reason, the patient was referred to our critical care center. Upon admission to our center, a physical examination revealed no abnormalities, but neurological examination disclosed left hemiparesis. CT scans revealed a large mass lesion of a low to high density in the right basal ganglia, accompanied by midline shift and ventricular dilatation. Elevation of human chorionic gonadotrophin (HCG) and alpha-fetoprotein (AFP) in both serum and cerebrospinal fluid (CSF) was observed. The tumor with multiple cysts was removed totally by craniotomy. The removed tissue was rated histopathologically as mixed-type germ cell tumor composed of germinoma and embryonal carcinoma. The removed tumor cells were found immunohistologically to contain HCG and AFP. Postoperative CT scans showed complete disappearance of the tumor. Taking into account a recent report that a combined cisplatin and etoposide therapy (PE chemotherapy) was effective in treating intracranial germ cell tumors, we used this chemotherapy for postoperative management of this patient. The patient underwent 3 cycles of PE chemotherapy during the 3 months after surgery. The elevated HCG and AFP levels in serum and CSF returned to their normal range within 2 months after surgery. CT and tumor markers revealed no signs of recurrence.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMed1994

[Idiopathic dural arteriovenous fistula of the superior sagittal sinus associated with intracerebral hemorrhage: a case report].

A case was reported of a surgically removed idiopathic dural arteriovenous fistula of the superior sagittal sinus associated with intracerebral hemorrhage. Dural arteriovenous fistula of the superior sagittal sinus is said to be rare. Only 9 cases have been reported in detail so far. A 46-year-old male was referred to our clinic complaining of left motor weakness of sudden onset. He had no history of head injury. CT scan revealed subcortical hemorrhage in the right frontal lobe. enhanced CT scan showed string-like enhancement in the margin of the hemorrhage. Right internal carotid angiogram disclosed a dural arteriovenous fistula, of which the feeding artery was a meningeal branch of the posterior ethmoidal artery, draining the superior sagittal sinus and right frontal superficial cortical vein. The superior sagittal sinus was not obstructed. It was diagnosed as a rare idiopathic dural arteriovenous fistula in the superior sagittal sinus. Surgical obliteration of an arteriovenous fistula was performed preserving the superior sagittal sinus. Etiological aspects and surgical management of the rare lesion was discussed referring to previous reports.

Adult↗
PubMed1994

[A case of Hangman's fracture associated with vertebral arteriovenous fistula treated with trapping].

A case of a traumatic vertebral arteriovenous fistula associated with a hangman's fracture is reported. A 45-year-old male fell down about 2 meters and struck his parietooccipital region against the ground. Profuse nasal bleeding developed. He was transferred to a local hospital, where his respiration was ataxic and blood pressure was low. After intubation, he was transferred to our emergency department. Cervical x-p revealed fracture of C1, C2 and subluxation of C2 body. Because of uncontrollable nasal bleeding, the bilateral maxillary arteries were embolized with spongel. At this time, right vertebral angiograms demonstrated a vertebral arteriovenous fistula with an pseudoaneurysm located at C2 level. On the 13th hospital day, direct balloon occlusion of the fistula was attempted; this could not be achieved because the subclavian and vertebral arteries were tortuous and the balloon catheter could not be introduced to the level of the fistula in the vertebral artery. The patient was only observed until follow-up angiogram on the 24th hospital day revealed enlargement of the pseudoaneurysm. We performed trapping of both the proximal and distal ends of the involved vertebral artery; from C5 to C1. Postoperative course was uneventful, hangman's fracture was fixed with a Halo vest. Four months after operation, fistula and pseudoaneurysm were not opacified on angiogram. We believe that transvascular techniques are the treatment of choice for vertebral arteriovenous fistulas. However, as the next best thing, we can use trapping for the patient whose vessels are too tortuous to introduce the balloon catheter to the involved vessel.

Arteriovenous Fistula↗
PubMed1994

[A multicentric glioma exhibiting three supratentorial lesions].

We reported a multicentric glioma having three separate lesions in the cerebrum. A 75-year old man was hospitalized with progressive disorientation. Computed tomography demonstrated two lesions in the left temporal lobe and the right frontal lobe. Magnetic resonance image disclosed one more lesion in the right occipital lobe. 2-staged operative procedures were performed for the left temporal and the right frontal tumors. It was histologically proven that one was glioblastoma and the other was anaplastic astrocytoma. The patient subsequently underwent radiotherapy and chemotherapy. Most multicentric gliomas are diagnosed in autopsy. Therefore it should be stressed that diagnosis is best made by biopsy or surgery. We discussed what therapy we should use for this fatal disease.

Aged↗
PubMed1994

Establishment and characterization of a human tongue cancer xenograft line in nude mice.

We established a human tongue cancer (well-differentiated squamous cell carcinoma) xenograft line, LK-1, in nude mice. LK-1 showed logarithmic growth from 5 to 7 weeks after transplantation, and the take rate for 25 generations was 95.0%. We confirmed the expression of cytokeratins 1, 5, 7, 10, 14, 16, 17, 18 and 19, and type I, III, IV and V collagens by electrophoretical and immunohistochemical analyses. Although the amount of type I, IV and V collagens increased gradually from 5 weeks after transplantation, the distribution of type IV collagen was often discontinuous in the cancer basement membrane. From these data we concluded that LK-1 is an excellent model for the investigation of the cell biology of well-differentiated oral squamous cell carcinoma, and for examining the effects of clinical therapies for this disease.

Adult↗